Process for selective hydrogenation of highly unsaturated compounds

ABSTRACT

A process for the selective hydrogenation of cyclododecatriene to produce cyclododecene in the presence of hydrogen at a temperature from 100* to 300*C using,as a catalyst, a cobalt complex compound having three ligands of carbon monoxide and one ligand of phosphine per one atom of cobalt.

United States Patent 91 Misono et al.

[ 1 Feb. 6, 1973 [S4] PROCESS FOR SELECTIVE HYDROGENATION OF HIGHLY UNSATURATED COMPOUNDS [75] Inventors: Akira Misono; Ikuei Ogata, both of Tokyo, Japan [73] Assignee: Nippon Oil Tokyo, Japan [22] Filed: 7 Dec. 22, 1970 [21] Appl. No.: 100,844

Related US. Application Data [63] Continuation-impart of Ser. No. 772,416, Oct. 31,

1968, abandoned.

[30] Foreign Application Priority Data Nov. 6,1967 Japan ..42/70924 52 U.S.Cl. ..260/666A [51] Int.Cl. ..C07c5/l4,C07c5/16 Company Limited,

Primary Examiner-Delbert E. Gantz Assistant Examiner-Veronica OKeefe AttorneyWenderoth, Lind & Ponack [57] ABSTRACT A process for the selective hydrogenation of cyclododecatriene toproduce cyclododecene in the presence of hydrogen at a temperature from 100 to 300C using,as a catalyst, a cobalt complex compound having three ligands of carbon monoxide and one ligand of phosphine per one atom of cobalt.

4 Claims, No Drawings 1 PROCESS FOR SELECTIVE HYDROGENATION OF I HIGHLY UNSATURATED COMPOUNDS This application is a continuation-impart of copending application, Ser. No. 772,416 filed Oct. 31, 1968 now abandoned.

This invention relates to a novel process for a selective hydrogenation of cyclododecatriene to produce cyclododecene,-using as the catalyst a cobalt complex compound having three ligands of carbon monoxide and one lignad of phosphine per one atom of cobalt.

A process of selective hydrogenation of a highly unsaturated compound having two or more of unsaturated bonds to a monoene compound without changing the carbon chain structure, or a process of selective hydrogenation of a highly unsaturated compound which coexists with 'monoenes is of high industrial value, and for a long time satisfactory process for effecting such selective hydrogenation has extensively been looked for. Especially selective hydrogenation of cyclododecatriene to produce cyclododecene has been looked for.

In general, most of prior studies on the hydrogenation of unsaturated compounds have been made using Ni, Pd, Pt and the like as the catalyst. These catalysts however exhibit but little selectivity in the hydrogenation of highly unsaturated compounds so that hydrogenation proceeds to completely saturated compounds and it is difficult to obtain monoene compounds retaining one unsaturated bond with good selectivity. Consequently, trials have been made to effect selective production of monoene compoundsusing hydrogenation catalysts of other types. Many of such catalysts are solid hydrogenation catalysts having modified compositions or solid hydrogenation catalysts to which an addition agent has been added to control the activity to some extent and to produce selectivity. But selectivity obtained with such catalysts was unsatisfactory. 1

For example, a method of selective hydrogenation. using M08 MS and the like is described in J.A.C.S., 337,74(l952; a method using reduced nickel is described in U.S. Patent No. 3,244,854; a method using M8 is described in British Pat. No. 1,028,499, and a method using Raney nickel is described in French Pat. No. 1,857,114. However, selectivity attained in these methods are poor and large amounts of byproducts such as saturated hydrocarbon, and decomposed and/or polymeric products are formed.

U.S. Pat. No. 3,303,228 describes hydrogenation for.

a short period'in a tubular reactor using cobalt carbon yl as the catalyst. However, this method requires reaction'conditions of 150 2509C under 100 atm. in the presence of a considerable amount of catalyst. Yet the selectivity is poor and considerable amounts of saturated hydrocarbon and other byproducts are formed. U.S. Pat. No. 3,308,117 describes hydrogenation using cobalt carbonyl as the catalyst in the presence of carbon monoxide. This method requires similar reaction conditions as those of U.S. Pat. No. 3,308,228 and has also the disadvantage of forming large amounts of oxygenated compounds as the byproducts.

While, a hydroformylation process usingcobalt carbonyl complex catalyst is disclosed in British Pat. No. 1,049,291 and hydrogenation of unsaturated compound using also cobalt carbonyl complex catalyst is disclosed in British'Pat. No. 942,435, however, there is no disclosure at all about the process for the selective hydrogenation of cyclododecatriene to produce cyclododecene, which has been accepted by those skilled in the art as one of the most difficult process up to now.

An object of this invention is to provide a novel process for the selective hydrogenation of cyclododecatriene to produce cyclododecene which does not have the disadvantages of prior processes and which has notdesclosed before. Further object of this invention is to provide a novel process for the selective hydrogenation of cyclododecatriene to cyclododecene with a selectivity above 99 percent under mild reaction conditions.

Above objects have been attained according to this invention by hydrogenating a cyclododecatriene in'the presence of hydrogen at a temperature from 100 to 300C using, as a catalyst, a cobalt complex compound having three ligands of carbon monoxide and one ligand of phosphine per one atom of cobalt.

The term phosphine" used herein is to include phosphorus compounds whichmay be regarded as derivatives of PH;,, i.e. phosphorus compounds having aliphatic, cycloaliphatic and/or aromatic radicals bonded by any of the three valencies of the phosphorus atom.' Typical examples of such phosphines are trimethylphosphine, triethylphosphine, tri-n-butylphos phine, diethylcyclohexylphosphine, triphenylphosphine, tritolyphosphine and the like. Phosphine described herein can also have two or more than two valencies of phosphorus atom satisfied by one hydrocarbon radical, for example, two valencies by one alkylene radical. Phosphine described herein may also be a polynuclear phosphine containing two or more than two phosphorus atoms.

Catalyst used in the process of this invention is a cobalt complex having three ligands of carbon monoxide and one ligand of phosphine per one atom of cobalt, i.e. a cobalt complex having three carbonyl groups and one phosphine group as the coordinating groups connected to cobalt atom each at least by one coordination linkage. Commonly, such cobalt complex isderived from cobalt carbonyl by replacing some of the carbonyl groups of the cobalt carbonyl by phosphine and someof the remaining carbonyl groups by hydrogen and/or an organic group. Examples of such cobalt complex which may be used as catalyst in the process of this invention are HCo(CO) (Phosphine), [Co(CO) (Phosphine)],, (Alkyl- )Co(CO) (phosphine), (Aryl-)Co(CO) (Phosphine), (Acyl)C0(CO)=i(Phosphine), [Co(CO) (Phosphine) [Co(CO) and the like.

According to this invention, cyclododecatriene is hydrogenated in the presence of hydrogen using above described catalyst in a solvent or without using solvent.

Use ofa catalyst system which will produce such cobalt complex in the reaction system is also within the scope of this invention. For example, cobalt carbonyl and phosphine can be introduced into the reaction system separately to produce the active cobalt complex in the mixture.

We have found that when cyclododecatriene is hydrogenated in' the presence of cobalt complex described above, cylododecene is obtained with a selectivity above 99 percent. We have also found that high catalytic activity of the cobalt complex and high yield of monoene compound can be obtained under mild conditions.

In order to make the nature of this invention more clear, presumed reaction mechanism involved in the process of this invention will be set forth below without intending to restrict the invention in any way thereby. Under the reaction conditions of this invention it can be thought that the cobalt complex is readily converted to its hydride which in turn adds to the vr-bonds of the highly unsaturated compound and activates the compound to take up hydrogen molecules for the effective hydrogenation. The behavior in this regard of the cobalt complex is higher than that of conventional hydrogenation catalyst such as Pt, Ni, MS and the like so that higher selective activity is obtained and the reaction can be proceeded at moderate reaction conditions. And it can also be thought that higher selectivity is due to the isomerization which readily takes place by the addition and reliberation of the cobalt complex hydride to and from the highly unsaturated compound under the reaction conditions of this invention. By this isomerization unsaturated bonds in the highly unsaturated compound are shifted to conjugated positions when they were not conjugated initially.

Conjugated diene structure resulting from this isomerization combines with the cobalt complex hydride and forms an intermediate complex having high coordination stability in preference to non-conjugated and monoene structures. Intermediate complex of the diene structure and cobalt complex thus formed activates hydrogen molecules in the reaction system and promotes the diene structure to take up the hydrogen molecules to add to the unsaturated bonds. It can be thought that when the conjugated diene structure in the intermediate complex is hydrogenated to monoene structure the intermediate complex is deactivated and the cobalt-complex hydride is re-liberated. The re-liberated cobalt complex is now taken up in coordination with diene structure remaining in the reaction mixture.

Accordingly, so long as highly unsaturated compounds having higher unsaturation remain in the reaction mixture, hydrogenation to monoene structure continues and hydrogenation of monoene structure does not take place until all of the highly unsaturated compounds having higher unsaturation than monoene structure are consumed.

In our copending U.S. Pat. application Ser. No. 547,795 entitled Selective hydrogenation using transition metal catalyst" there is described a process for the selective hydrogenation of polyene compounds to monoene compounds using a catalyst system prepared by reducing a complex compound soluble in organic solvent of transition metal of group VIII of the Periodic Table with triethylaluminum and the like. Some polyene compounds having certain structure did not show good reactivity in this process. For example, cyclododecatriene which, due to the carbon atom skeletal structure of the molecule, cannot have perfectly plane conjugated diene structure by isomerization, did not show good reactivity. It has been found that when the catalyst system of this invention is used, not only common highly unsaturated compounds but also highly unsaturated compounds which are difficult to take perfectly plane diene structure on isomerization can he hydrogenated with excellent reactivity and selectivity to the corresponding monoene compounds. For example, cyclododecene is prepared satisfactorily from cyclododecatriene when a catalyst system containing [Co(CO) P(nC.,H,,) is used according to this invention. This is attributed to the presence of phosphine in the catalyst as one ligand.

The process of this invention can be conducted at a temperature within the range of 300C and under autogeneous or a hydrogen pressure of 0 100 atm. Pressure governs only the reaction rate. The process of this invention may be carried out in the presence of a solvent or without using solvent. Solvent, when used, may be any of common organic and inorganic solvents provided it does not deactivate the catalyst significantly under the reaction conditions. Particularly useful solvents are tetrahydrofuran, alcohols, dialkylethers, esters, aromatic and aliphatic hydrocarbons, etc.

In order to carry out the process of this invention effectively, it is preferred to stop the reaction at a point at which the reaction mixture still contains highly unsaturated compounds in amount significantly above equimolar to the amount of catalyst. Alternatively, fresh highly unsaturated compound may be added before highly unsaturated compounds disappear or a lower diolefin such as butadiene or isoprene may be added to the reaction mixture in an amount above equimolar to the amount of catalyst to prevent overhydrogenation ofthe monoene compound.

Reaction mixture in which the reaction has been stopped at a point at which the mixture still contains highly unsaturated compounds in amount significantly above equimolar to the amount of catalyst or in which overhydrogenation of the monoene compound has been stopped by the addition ofa lower diolefin is then subjected to conventional procedure such as stripping to recover the disired monoene compound. Catalyst is recovered as an oily residue. The recovered catalyst was found to have similar activity as the fresh catalyst when reused and it is one feature of this invention that the catalyst can be recovered and reused in such manner.

The following examples are presented for the purpose of illustrating this invention and advantages thereof. It will be understood that this invention is not limited by these examples.

EXAMPLEI 50 ml autoclave equipped with an agitator was dried and purged with dry nitrogen gas and 1.9 millimols ofa cobalt complex consisting essentially of [Co(CO) P (nBu) prepared by reacting 3 millimols of octacar- Table I 7 Component by weight Cyclododecane 0.4 trans-Cyclododecene 67.7 cis-Cyclododecene 31.9 Cyclododecadiene O Cyclododecatriene 0 oxygenated compounds 0 EXAMPLE II In an autoclave having a capacity of 50 ml which has preliminarily been dried and purged with nitrogen, 20 ml of n-hexane, 66 millimols of 1,5,9- cyclododecatriene, 0.88 millimol of octacarbonyl dicobalt and 3.4 millimols of trimethylphosphine were placed. Then hydrogen was introduced to a pressure of 30.0 atm. Temperature was raised by heating and at 140C hydrogen absorption was observed to commence. Reaction was continued for a period of 20 minutes with addition of hydrogen. Pressure at the end of the reaction period was 28.6 atm. Reaction was stopped by quenching.

The reaction mixture was analyzed by gas chromatography. No metallic cobalt was detected. As comparison same procedure was repeated except that the 1 addition of phosphine was omitted. In this case, hydrogen absorption commenced at 130C. but stopped immediately and again commenced when the temperature was raised to 160C. Precipitation of metallic cobalt was observed.

Results of the analysis of the reaction mixtures are Catalysts containing no phosphine COMPARATIVE EXAMPLE I A selective hydrogenation of cyclododecatriene using a compound I-ICo(PBu as a catalyst was intended. The experiment could not be carried out because l*ICo(P B u is unstable except in the extremely low temperature condition.

COMPARATIVE EXAMPLE II H Co(P represents phenyl group) was used as a catalyst.

A catalyst ,H Co(P in the amount of 20mg which was obtained by causing to react cobalt acetylacetonato (Co(-AcAc) ter-butylaluminium (Al(ter-Bu) and excess triphenylphosphine under normal temperature; I ml of l,5,9-cyclododecatriene; and 5 ml of benzene, was previously dried and they were introduced into 50 mol autoclave with agitator which was filled with nitrogen gas, and caused to react for 1 hour at a temperature of about 80C and a pressure of 50 atm. with a supply of hydrogen gas.

' The reaction products were as follows:

Cyclododecane 16 wt% Cyclododecenes 41 wt% Cyclododecadiene 27 wt% Cycldodecatriene 16 wt% From this result, it was understood that the selectivity of this reaction was inferior because considerable amount of cyclododecane was produced while unreacted cyclododecatriene, remained.

COMPARATIVE EXAMPLE III HCo(CO)(P;,) was used as a catalyst, which was I obtained by causing the catalyst used in the Comparative Example 11 to react with carbon monoxide, and

hydrogenation was carried out in the same conditions as Comparative Example 11 except that the reaction temperature was raised. The reaction started at a temperature of 150C and the reaction was continued for 2 hours.

The reaction products were as follows:

' Cyclododecane 10 wt% Cyclododecenes 60 wt% Cyclododecadiene 25 wt% cyclododecatriene 5 wt% As similar as the Comparative Example 11, the catalyst of this Example was not good in the selectivity.

COMPARATIVE EXAMPLE IV HCo(CO) (P was used as a catalyst.

Into an autoclave as used inComparative Example 11; 32 mg of [Co(CO) 98 mg of P (P/Co 2) and 5 ml of toluene were fed, and further hydrogen gas was introduced up to 37 atm., Then they were kept at a;

temperature of C for 1 hour. Thus I-ICo(CO) (P was produced in the reaction system, and then 2.5 m1 of,

cyclododecane 4 wt% Cyclododecenes 51 wt% Cyclododecadiene 30 wt% Cyclododecartiene 15 wt% As the result of this example, it will be understood that the selectivity of the catalyst is not good as well as that the catalytic activity thereof is inferior. It is considered that said inferior catalytic activity is due to the fact that one of phosphine which is a ligand of the COMPARATIVE EXAMPLE v Cyclododecane 45 wt% Cyclododecenes 35 wt% Cyclododecadiene 7 wt% Cyclododecatriene 13 wt% As the result of the above, it is understood that the catalyst of this Example is inferior not only in the selectivity but also in the catalytic activity and that the catalyst is decomposed.

COMPARATIVE EXAMPLE VI Into an autoclave as used in Comparative Example 11, 131 mg (0.33 m mol) of 1,2-bis(diphenylphosphino)ethane, 56.6 mg (0.165 m mol) of [Co(CO) and ml of benzene were fed, and further hydrogen gas was introduced, then they were caused to react under the conditions of at a temperature of 100C, at a pressure of 45 atm. and for 50 minutes, thus the catalyst was prepared, thereafter 3 ml of 1,5,9- cyclododecatriene was added and the temperature was raised. At 150C, hydrogen was consumed which show ing the start of hydrogenation reaction, and even the temperature was raised up to 180C, the consumption of hydrogen was very slow. At last after 2 hours from the start of the reaction, the reaction proceeded no more.

The reaction products were as follows:

used as a Cyclododecatriene It is understood from this result that the catalyst of this Example is inferior not only in the selectivity but also in the catalytic activity. It is considered that the catalyst decomposed in the reaction system.

COMPARATIVE EXAMPLE Vll HCo(CO) P(CH 2) was used as a catalyst.

. Into an autoclave as used in Comparative Example 11, 103 mg (0.27 m mol) of 1,4-bis(diphenylphosphino)butane, 41.5 mg (0.12 m mol) of [Co(CO),,] and 4 ml of toluene were fed, and further hydrogen gas was introduced and the mixture was caused to react at a temperature of C, at a pressure of 35 atm. and for 30 minutes, thus the catalyst was produced. Then, 1 ml of cyclododecatriene was added into said mixture and the temperature was raised. The reaction started at 165C, owever, the consumption of hydrogen was slow, and then the temperature was raised up to C, however, the reaction stopped after 60 minutes.

The reaction products were as follows:

Cyclododecanc 4 wt% Cyclododccencs 47 wt% Cyclododecadiene 43 wt% Cyclododecatriene 6 wt% As same as Comparative Example V1, the catalyst of this Example was inferior in the selectivity and activity.

What is claimed is:

1. A process for the production of cyclododecene by the selective hydrogenation of cyclododecatriene which consists essentially of contacting cyclododecatriene with hydrogen at a temperature from 100 to 300C using, as a catalyst, a cobalt complex compound having three ligands of carbon monoxide and one ligand of phosphine per one atom of cobalt.

2. A process according to claim 1, in which the reaction is terminated when substantially all of cyclododecatriene has been converted to cyclododecene.

3. A process according to claim 1, in which the catalyst is formed in the reaction system;

4. A process according to claim 2 in which the catalyst is formed in the reaction system. 

1. A process for the production of cyclododecene by the selective hydrogenation of cyclododecatriene which consists essentially of contacting cyclododecatriene with hydrogen at a temperature from 100* to 300*C using, as a catalyst, a cobalt complex compound having three ligands of carbon monoxide and one ligand of phosphine per one atom of cobalt.
 2. A process according to claim 1, in which the reaction is terminated when substantially all of cyclododecatriene has been converted to cyclododecene.
 3. A process according to claim 1, in which the catalyst is formed in the reaction system. 